This invention relates to a tracking controlling apparatus, and more particularly to a tracking controlling apparatus of an automatic tracking following system (ATF system) wherein pilot signals recorded on information recording tracks formed on a record medium are reproduced by a reproducing head in order to cause the reproducing head to track reproducing tracks in accordance with such pilot signals thus detected.
Conventionally, an ATF system such as disclosed in U.S. Pat. No. 4,297,733 is known as a system for achieving phase-servoing of a capstan system of a video tape recorder (VTR). In this system, relative phase positions between a reproducing head and pilot signals continuously or intermittently recorded on information recording tracks of a tape as a record medium are detected to correct errors therebetween in order to control the speed of a capstan motor and hence the speed of travel of the tape. According to the system, while it is relatively easy to attain accurate tracking lock of a reproducing head to individual tracks, it is difficult to attain tracking lock to a position on the tape which is displaced from individual tracks.
Conventionally in VTRs, however, it is sometimes desired to lock a reproducing head to a position displaced from individual tracks if necessary such as when a reproducing head is to be set to a desired track for after recording or when crosstalk is to be measured relative to the magnitude of tracking displacement in order to effect adjustment of a VTR. From this point of view, apparatus of the system are not satisfactory in function.
As a second system which can solve this problem, a control signal system (CTL system) is known. In this system, timing pulse signals which are recorded in prior as control signals on a tape along a direction of travel of the tape are reproduced by means of a specific control signal reproducing head and a capstan motor is controlled in accordance with a result of comparison between the phase of control signals thus reproduced and the phase of reference pulses which are produced independently. In the system, the phase of reference pulses can be delayed by means of a controllable element such as, for example, an element which is called a tracking control volume. Thus, tracking lock points can be easily displaced in this system. According to the CTL system, however, a tape must be provided with a specific track on which control signals are recorded, and besides, a fixed head for reproducing such control signals from the specific track must be provided in addition to recording and reproducing heads for video signals; thus, the system is disadvantageous in that constructions associated with a tape must be complicated when compared with the ATF system.